RuleSet's hash map hashes by identity of TrustedOrigin and not by value. RulesSet attempts to add to an immutable list if trustedorigins are equal

biscuit-core/src/main/java/org/eclipse/biscuit/datalog/RuleSet.java

@@ -20,7 +20,7 @@ public RuleSet() {
 
   public void add(Long origin, TrustedOrigins scope, Rule rule) {
     if (!rules.containsKey(scope)) {
-      rules.put(scope, List.of(new Pair<>(origin, rule)));
+      rules.put(scope, new ArrayList<>(List.of(new Pair<>(origin, rule))));
     } else {
       rules.get(scope).add(new Pair<>(origin, rule));
     }

biscuit-core/src/main/java/org/eclipse/biscuit/datalog/TrustedOrigins.java

@@ -7,6 +7,7 @@
 
 import java.util.HashMap;
 import java.util.List;
+import java.util.Objects;
 
 public final class TrustedOrigins {
   private final Origin origin;
@@ -91,6 +92,25 @@ public String toString() {
     return "TrustedOrigins{inner=" + origin + '}';
   }
 
+  @Override
+  public boolean equals(Object o) {
+    if (this == o) {
+      return true;
+    }
+    if (o == null || getClass() != o.getClass()) {
+      return false;
+    }
+
+    TrustedOrigins trustedOrigin = (TrustedOrigins) o;
+
+    return Objects.equals(origin, trustedOrigin.origin);
+  }
+
+  @Override
+  public int hashCode() {
+    return origin.hashCode();
+  }
+
   public Origin getOrigin() {
     return origin;
   }

biscuit/src/test/java/org/eclipse/biscuit/datalog/WorldTest.java

@@ -5,6 +5,7 @@
 
 package org.eclipse.biscuit.datalog;
 
+import static org.junit.jupiter.api.Assertions.assertDoesNotThrow;
 import static org.junit.jupiter.api.Assertions.assertEquals;
 import static org.junit.jupiter.api.Assertions.assertTrue;
 
@@ -762,4 +763,38 @@ public void testResource() throws Error {
     }
     assertTrue(res.size() == 0);
   }
+
+  @Test
+  public void testAddRuleEqualButDistinctTrustedOriginsDoesNotThrow() {
+    final World w = new World();
+    final SymbolTable syms = new SymbolTable();
+
+    final long left = syms.insert("left");
+    final long straight = syms.insert("straight");
+    final long right = syms.insert("right");
+    final Term.Variable a = new Term.Variable(syms.insert("a"));
+    final Term.Variable b = new Term.Variable(syms.insert("b"));
+
+    final Rule r1 =
+        new Rule(
+            new Predicate(left, Arrays.asList(a, b)),
+            Arrays.asList(new Predicate(right, Arrays.asList(a, b))),
+            new ArrayList<>());
+    final Rule r2 =
+        new Rule(
+            new Predicate(straight, Arrays.asList(a, b)),
+            Arrays.asList(new Predicate(right, Arrays.asList(a, b))),
+            new ArrayList<>());
+
+    System.out.println("adding r1: " + syms.formatRule(r1));
+    System.out.println(
+        "adding r2 under an equal but distinct TrustedOrigins instance: " + syms.formatRule(r2));
+
+    assertDoesNotThrow(
+        () -> {
+          w.addRule(1L, TrustedOrigins.defaultOrigins(), r1);
+          w.addRule(1L, TrustedOrigins.defaultOrigins(), r2);
+        });
+    assertEquals(1, w.getRules().getRules().size());
+  }
 }